Variable Gear Transmission for Aircraft Fuel Pump Pressure Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Centrifugal pumps in fuel systems for aircraft face insufficient discharge pressure at low engine rotational speeds, leading to energy inefficiency and increased complexity when using a fixed volume pump as a backup.
Innovation Solution
A fuel system with a centrifugal pump connected to the engine via a transmission that regulates gear ratio, allowing for adjustable rotational speed of the centrifugal pump, along with sensors and controllers to maintain optimal pressure and flow, eliminating the need for a fixed volume pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a centrifugal pump is driven directly by the engine, then the system complexity is reduced and energy efficiency is improved, but the discharge pressure becomes insufficient at low engine rotational speeds
Solution Approach 1:
The patent applies a variable gear ratio transmission mechanism that dynamically adjusts the rotational speed of the centrifugal pump based on engine speed. At low engine speeds, the transmission increases the pump's rotational speed to maintain sufficient discharge pressure, while at high engine speeds, it allows direct coupling for simplicity and efficiency. This dynamic adjustment resolves the contradiction between system simplicity and pressure sufficiency across varying operating conditions.
2Stress or pressure
If a fixed volume pump is installed to ensure sufficient discharge pressure at low engine speeds, then the discharge pressure is improved, but the system complexity and size increase due to the need for a switching mechanism
Solution Approach 1:
Instead of using a fixed volume pump with switching mechanisms, the patent employs a single centrifugal pump with a variable gear ratio transmission that dynamically adapts its speed ratio. This eliminates the need for multiple pumps and switching mechanisms, maintaining sufficient discharge pressure at low speeds while avoiding the complexity and size increase that would result from adding a fixed volume pump and control system.
3Stress or pressure
If a fixed volume pump is used, then sufficient discharge pressure is obtained at low engine speeds, but energy effectiveness is reduced due to pressure energy conversion into heat during fuel return
Solution Approach 1:
The variable gear ratio transmission enables the centrifugal pump to operate at optimal rotational speeds across all engine conditions, maintaining sufficient discharge pressure without requiring a fixed volume pump. This eliminates the need for pressure relief valves and fuel return systems that convert pressure energy into heat, thereby preserving energy effectiveness while ensuring adequate pressure at low engine speeds.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures sufficient discharge pressure at low engine speeds without a fixed volume pump, enhancing energy efficiency and reducing system complexity by modifying the centrifugal pump's rotational speed and pressure control.
Implementation Method 1
a centrifugal pump which pressurizes and delivers fuel that is supplied to an engine of the aircraft
Implementation Method 2
a transmission which connects the engine and the centrifugal pump to each other, is able to regulate a gear ratio and which modifies and transmits a rotational speed of a rotational power that is output from the engine to the centrifugal pump
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A fuel system (1A) includes a centrifugal pump (2a) which pressurizes and delivers fuel (N) that is supplied to an aircraft engine (E), and a transmission (2c) which connects the engine (E) and the centrifugal pump (2a) to each other, is able to regulate a gear ratio and which modifies and transmits a rotational speed of rotational power that is output from the engine (E) to the centrifugal pump (2a).